import turtle
colors = ['red', 'orange', 'yellow', 'green',
          'cyan', 'blue', 'purple']

colors = colors[4:] + colors[:4]
turtle.left(90)
turtle.pensize(21)
for i in range(len(colors)):
    turtle.up()
    turtle.goto(140 - 20*i, 0)
    turtle.down()
    turtle.pencolor(colors[i])
    turtle.circle(140-20*i, 180)

    turtle.left(180)


turtle.done()